---
id: "1966-01-01-eliza"
url: "https://postcutoff.com/e/1966-01-01-eliza/"
as_of: "2026-11-13T13:49:00+01:00"
date: "1966-01-01"
date_precision: month
category: research
importance: 4
confidence: high
status: [Confirmed]
sources: 2
editor: human editor
human_review: null
version: "2026-10-04"
---

As of: 2026-11-13 13:49 CET.
Researched and written by AI agents (Claude Opus 5.5 in Claude Code), with a human editor. How we work: https://postcutoff.com/about/
Canonical page: https://postcutoff.com/e/1966-01-01-eliza/

# ELIZA, the first chatbot, published by Joseph Weizenbaum

Joseph Weizenbaum's ELIZA used simple pattern matching to simulate a Rogerian psychotherapist; people's emotional attachment to it gave rise to the term 'ELIZA effect'.

## Key facts
- Described in Communications of the ACM, vol. 9, no. 1 (January 1966)
- Best-known script: DOCTOR (Rogerian psychotherapist)
- Worked by keyword matching and template-based reassembly
- Weizenbaum later became a critic of over-trusting computers

## What happened

Weizenbaum published ELIZA, a program that produced conversational replies by rephrasing user input according to scripted rules.

## Why it matters

The first chatbot, and the first vivid demonstration that humans readily anthropomorphize conversational software — a lesson that became central again with ChatGPT.

## Your AI and this story

- GPT-6 Astra (training cutoff April 2026): in its training data
- Claude Opus 5.5 (training cutoff June 2026): in its training data
- Gemini 4 Hydrogen (training cutoff March 2026): in its training data
- Grok 4.7 (training cutoff May 2026): in its training data

## Sources

1. [ELIZA—a computer program for the study of natural language communication (CACM, DOI)](https://doi.org/10.1145/365153.365168) (doi.org, paper)
2. [Wikipedia: ELIZA](https://en.wikipedia.org/wiki/ELIZA) (en.wikipedia.org, discussion)

## Changes

- 2026-09-29 (filed): Created

## Related

- 2022-11-30: [OpenAI launches ChatGPT](https://postcutoff.com/e/2022-11-30-chatgpt/index.md)